Hello Richard, while planing a multiday trip, I noticed that gradient display (in the 2d view) breaks.
for instance on this route: https://cycle.travel/map/journey/306662 around kilometer 190, it doesn't show any color, and the tooltip on the line of the 2D view doesn't show the percentage like it usually does (can't screenshot the tooltip as it disapears). however this is actually a very steep climb albeit for my touring standards.
Now if I draw only that segment of the road in a new tab, it show correctly ( https://cycle.travel/map/journey/316733 ):
while experimenting I've noticed the tooltips start to break at around 150km as for the coloring, I haven't really found a logic as to when it breaks. Also note that zooming in on the elevation chart doesn't help.
hope this helps!
Comments
I was just going to post about this as have had the same problem. The gradient was showing fine at first but after I saved the route it disappeared. So I tried uploading a gpx file of the route which also didn't show the gradient.
It’s somewhere between “intentional” and “known issue”!
Elevation data is both slow (i.e. takes the server a while to calculate) and heavy (i.e. there’s a lot of it, so it takes a while to transmit from the server to your browser).
To minimise the effects of that, above a certain distance, cycle.travel switches over to return only a maximum number of altitudes (roughly 2000 per journey). That keeps the calculation snappy and doesn’t boggle the server too much.
The downside is that it can’t then calculate the gradient reliably, because in the extreme case like a 6000km trans-American route, the altitudes might be 3km apart… and there might be any number of ups and downs in that section. That’s why the tooltip stops showing the gradient on the longest routes.
It’s something I’d like to look at in the future – there aren’t really any easy answers, but that’s not to say there might not be complicated ones!
(And just to clarify, the full gradient is still used in calculating the route.)
Thanks for the reply. I understand. I'll keep using the split-by-day to scout for gradient traps for now then.
I imagine moving that calculation to the frontend wouldn't be an easy solution?
thanks for your work and the quick reply.
Speaking of gradient and frontend:
cycle.travel/map/journey/320655
illustrates a strange behavior
The gradient is shown correctly after loading .. but jumps significantly when the via point is moved slightly
After save and reload its back to normal again